A research team has managed to coordinate 100 domestic air conditioners to stabilise the power grid in real time, as if they were a flexible power plant.

Jun 14, 2025 Last reply: 1 year ago 16 Replies

This is an automated translation (DeepL) of an article I found today; the original is in Spanish. There is an article in English at the IEEEE, but you need an account to read.



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*A research team has managed to coordinate 100 domestic air conditioners to stabilise the power grid in real time, as if they were a flexible power plant.*


5-6 minutes



A research team demonstrated that many residential air conditioners can be coordinated to support the power grid without affecting the comfort of users.


Air conditioning: from enemy to ally



  • Air conditioning use = more electricity demand in summer. * Peak consumption → risk of blackouts. * New system: controls ACs without affecting comfort. * Technology tested in 100 homes (Texas). * Results: regulates the grid like a power plant. * Zero nuisance for users. * Compatible with smart thermostats. * Contributes to integrating renewable energies.


How air-conditioning can help the grid instead of overloading it



In summer, the massive use of air conditioners generates peaks in electricity consumption. These peaks force expensive and polluting power plants to be activated, compromising grid stability and increasing carbon emissions. In some cases, this overload can even lead to blackouts or planned outages.



However, recent research shows that it is possible to transform this problem into a solution. Through intelligent control systems, it is feasible to coordinate the operation of hundreds of air conditioning units without affecting the comfort of users, while at the same time helping to stabilise the electricity grid.


Adjustable equipment, smart grids



Historically, the electricity grid was designed to operate with large thermal power plants (coal, natural gas, nuclear) that adjusted their output in real time according to demand. But with the increasing penetration of intermittent renewables (such as solar and wind), this model is no longer sustainable.



Today, the focus is on distributed energy resources: systems that generate, store or regulate energy consumption close to the end user. This is where electric vehicles, heat pumps, water heaters and smart air conditioners come into play, which can automatically modify their consumption without human intervention.


The problem of frequency



The electricity grid must be maintained at a constant frequency (60 Hz in North America). When demand exceeds generation, the frequency goes down; when there is excess generation, it goes up. Power plants adjust their output to maintain balance, a process known as frequency regulation.



But what if household appliances could also participate in this adjustment?


Pilot test: air conditioning as a frequency regulator



Between 2019 and 2023, a team led by the University of Michigan, together with Los Alamos National Laboratory and the University of California at Berkeley, conducted a pilot test in 100 homes in Austin, Texas. The air conditioners were connected to control boards capable of modifying the on/off cycle of the compressor depending on the frequency of the grid.



The adjustment was minimal: they always stayed within the temperature range defined by the thermostats. The aim was to achieve a collective change in electricity consumption, almost imperceptible to the users, but relevant to the electrical system.


Key results



  • Frequency regulation as accurate as that of a traditional power plant. * No discomfort reported by most users. * Indoor temperature never deviated more than 0.9°C from set point. * Less than 2% of households requested to deactivate the system in any test. * Full compatibility with smart thermostats already available on the market.


Incentives and adoption



This type of technology can be easily integrated into voluntary programmes offered by utilities or manufacturers of smart thermostats. In exchange for bill credits, the user allows their air conditioner to cooperate with the grid at critical times, without them noticing the difference.


Potential



Turning air conditioning into a flexible asset transforms a large energy consumer into a balancing and efficiency tool. Deploying it on a large scale would:



  • Reduce fossil fuel use at times of high demand. * Increase the capacity to integrate renewable sources (less reliance on backup power plants). * Reduce global emissions associated with summer electricity consumption. * Improve energy resilience to heat waves and consumption peaks. * Empower citizens to actively participate in the energy transition, without sacrificing their comfort.

This approach represents a smart, efficient and cost-effective way to move towards a cleaner and more balanced energy model.



More information: Controlling Air Conditioners for Frequency Regulation: A Real-World Example | IEEE Journals & Magazine | IEEE Xplore


Translated with DeepL.com (free version)


A/C units don't generate power. When renewables can't meet demand, the best they can do is load shed.

...

We all know that AC units don't generate power. You can read the IEEE paper, which is a serious document, and find out exactly what they did.

Pretty sure the point of the research was to find a simple way for air conditioners loading to be applied to the grid in a controlled fashion, rather than random starts and stops. This aids in keeping the loading factor under better control so another power generation source isn't needed to keep the line frequency stable.

What I've read sounds like good information for coordinating air conditioners across a wide area.

Nowhere in the post does it say that air conditioners are generating power...the reduction of fuel use is due to increased efficiency of power usage.

Isn't something like this used industrially for load balancing and scheduling? This is taking it to the homes...

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John :-#)#

Nuclear power plants also usually operate at 100% rated power so don't have any reserve either.

Steam in the boilers/heat exchangers acts as a reserve of energy for short-term stabilisation.

500,000 a/c units, cycling randomly, will be a very smooth load. About all that wide-range remote controls can do is crank down their total power. That would help, of course, when generation can't meet demand.

Seems easier to me to have adequate full-time generating capacity. That's an old-fashioned concept.

Improving efficiency by load shedding means hotter homes. Why not just mandate that no thermostats can go below 80F?

That's not what they are doing. They are changing the load in tiny parts of the cycle, 50 or 60 times per second. Changing the load waveform.

It can be dynamic. It doesn't have to be all the time.

PG&E operates a system they call SmartAC where they can remotely control the temperature of the air-conditioning to reduce grid stress to move consumption to times of less stress.

They will only do this during certain hours. In return the user gets some benefits.

Many thermostats have had those features for at least the last decade.

My ten year old Carrier thermostat addresses most of those items. It also has an exterior outside temperature sensor and takes in weather predictions over the internet so that it ramps the temperature appropriately and maintains a comfortable temperature and humidity.

The compressor protection is commonly built into the compressor control unit so that any command from the thermostat that compromises the compressor safety is ignored until safe.

That's just power factor adjustment. It doesn't generate power when the renewables slack off.

Seems like it would increase transformer losses too. 100 is a tiny sample size.

Sure. As the sun goes down and the wind doesn't blow, turn everybody's a/c off. That's better than rolling blackouts.

I don't know how many minutes prediction it does but it is supposed to do similar to what you describe. There is very little user control, just to enable or disable the feature.

That's what it's supposed to do. You set the times that you want it to be at the target temperature and it is supposed to learn and predict how much in advance to start heating/cooling. I have noticed that it starts operating at different times depending upon the weather/existing house temperature. I do have the room temperature logged by the home automation system and it seems to reach the target temperatures pretty much at the requested times.

There can be significant delay from manually altering the target point (for both enabling and disabling) but as the control input is not visible I don't know whether the thermostat or controller is doing that.

John Larkin does like to simplify issues down to a level that even he can understand. Turning everybody's a/c down a bit, rather than turning them off, is too subtle for him to comprehend.

I understand they are adjusting the frequency. My AC doesn't have a thermostat, it is continuously adjusted in tiny power adjustments with an inverter. Switching a thermostat on/off would destroy it.

It is not an ON/OFF thermostat, it is more likely a PID controller, probably implemented in software.

The result is that the compressor, once the target temp is reached, runs at low speed, matching the exact heat/cold wasted and maintaining a constant temperature. There is an inverter controlling the speed of the compressor.

No, if powered the air would flow, but the compressor would be stopped. Actually, the user would push a button in the remote, and the unit would generate heat instead.

Just because you can, doesn't mean it's a good idea.

Better just to distribute some kind of request and let the end user respond (or not).

Otherwise it's just one more thing that prevents operation or another com-hacking vulnerability.

RL

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